Electric switch construction



@ab 39, M434 l MENSENKAMP ET JECTRIG SWITCH CONSTRUCTION Filed July 6; 1942 2 ShaetSeShgai l Patented Oct. 19, 1943 ELECTRIC SWITCH. CONSTRUCTION Carlton B. Mensenkamp, Freeport, Ill., assigner to Micro Switch Corporation, Freeport, lll., a cory poration of Illinois Application July (ie 1942, Serial'No. 443,894

4 Claims.

IThe present invention relates to electric switches.

Objects of this invention include the provision of a rugged, compact, low cost electric switch con-y f struction,l suitable for use as a limit switchor the like, particularly for aircraft, the provision of such a switch which operates in response toa small motion of 'its actuating member while permitting a substantially-greater amountA of overtravel of the actuating member beyond the switch operating point thereof than has heretofore been' within the switch I8. It also has terminals.22 on l :its bottom face `(Figure 1).

An aperture in the side of the housing is tted with a conduit bush'- possible with switches of this character without increasing the dimensions of the switch, particuing 23 which opensinto the lower portion of the housing t'o permit conducting wires to be brought in easily for attachment to the terminals 22 of the switch. The unitary switch I8 itself may be lifted off its supporting pins kI9 while' the circuit wires are being fitted to it and then slipped back into place. n A

-'I'he space in the housing above the unitary switch I8 contains a mechanism for actuating the switch. This mechanism includes a reciprocal larly adapting the switch to certain aircraftl requirements, the provision of such a switch requiring a small operating effort and having inherent accuracy and reliability of operation, the provision of an improved. switch actuating mecha- `nism wherein space and weight are reduced to a minimum, and the provision of an improved elecinvention will become apparent from the following description of a specific embodiment thereof which serves by way of example to'illustrate the, manner in which the invention may be carried out, without thereby limiting the invention to the specific details of the example.

In the drawings:

Figure l is a side elevation'of a switch embodying my invention, with the cover and gasket removed and the operating plunger in the retracted position;

Fig. 2 is a fragmentary section through the upper portion of the switch `taken substantially on the line 2-2 of Fig. 5;

Fig. 3 is a section similar to Fig. 2 showing the position of the parts with the plunger moved inward to the end of its stroke;

Fig. 4 is a section substantially on the line 4-4 of Fig. 3, and

Fig. 5 is a fragmentary section on the line 5-5 of Figure 1.

In the drawings, a shallow die cast metal housing I2 is closed by a gasketed cover l5 (Figs. 4 and 5) held by screws I6 in the tapped holes Il, the housing having ilanges I 3 for attachment to a' support and a lining of insulation material I4 partly covering the inner surface. Withlnthe housing, a unitary elongated rectangular switch I8 ts accurately onto a pair of supporting pins I9 (Figure 1) This switch I8 may, vfor example, be of the type described in Patent 1,960,020 to P. K. McGall. Switch Ivhas a small operating pin 2l that projects vertically from its tcp and is adapted to be depressed for operating electric contacts 4I extends forward and carries a tab 48 'for entric switch construction. Other objects of the approximatelyv vertical arm 43 that extends .up

plunger 24 extending through the wall of the housing and supported partly in an enlargement or boss 25 in the wall of the housing and partly in an integral bracket 25 spaced slightly from the boss 25. A felt washer 2l held by a metal washer 28 and a spring 23, bearing against the bracket 26 provides a seal against oil and moisture. A bored hole 3| (Figs. 2 and 3) extends into the plunger 23 from its inner end 32 (left end as seen in the drawings). Into this bore yiit a compression spring 33 and a pilot rod 34 one within the `other. This pilot rod 34 and a strip 35 together 'constitute a rider 35 that is carried b'y the plunger 24. The strip 35 has a downturned tab 31 at its extreme forward end to which the pilot rod 34 is riveted, and has another downward extending tab `38 at its rearward 'end slidably iitting over the plunger 24.] With its tab 38 fitting the -outer serves as a stop fory preventing the rider 36 fromsliding forward (to the leftas seen in Figs. 1 to 4) off the end of the plunger. t

A bell crank l rides on a. pivot pin 42 which has its axis immediately below the pilot rod 34- and spring 33.l The bell crank lll includes an A tab 46 at the upper end of thev arm 53 extends over the top of the rider strip 35 to prevent the arm 43 from dropping out of its engagement with the notch 44. A second arm-41 of the bell crank Il. This construction gives the bell crank an effective lever arm that is longer than the slight spacing of the bell crank pivot 42 below the plunger 24.

A pair of pins 48 which fit into perforations in the downward extending forward tab of the strip Il serve to give lateral support to the extreme forward end of the rider 38 and also prevent its rotation about the axis of the plunger 24 so as to maintain the notch 44 of thestrlp Il in proper position for actuating the bell crank 4I. A coil spring 5I connected between the bracket 2l and the forward tab l1 of the strip 35 serves to retract the rider 36 and plunger 24 to their normal positions shown in Figs. 1 and 2 upon the release of actuating pressure from the plunger.

When the actuating plunger 24 is moved forward (toward the left) to the position shown in Figs. 3 and 4, the resulting forward motion of the rider 38 drives the bell crank 4I against the operating pin 2| of the switch I8 for operating it, the force transmitted through the spring 33. The resilience of the spring 33 permits the plunger 24 to continue its forward motion beyond the point at which the switch I8 operates simply by telescoping over the spring and pilot rod 34. The considerable "Overtravel motion of the plunger 24 can be noted in Fig. 3 where the plunger 24, moved to its extreme forward position, has carried the key 38 away from the end 38 of the rider I8 and to a point vadjacent the opposite end I1 of the strip 35.. 'l

The lower surface of Ithe tab 48 of the bell crank 4I is parallel to the axis of the'bell crank pivot 42 which in turn is parallel to each of 'the two supporting pins/I9 of the unitary switch 8. Accordingly, movement of the switch I8 on its two pins will not, by itself, bring the actuating pin 2l into engagement with a higher or lower spot of the bell crank tab 48. That is, movement of unitary switch I8 on its pins I9 cannot eect operation of switch I8 bythe plunger 24 and the bell crank 4I.

' Throughout the specication and claims, directional terms such as above, below, horizontal, vertical, forward, etc., are used for convenience and for indicating relative directions, and are not used in a restrictive sense.

It Awill be apparent to vthose skilled in the art that the present invention is capable of numerous modifications and variations, and that the particular embodiment herein shown and dcscribed serves simply as an example. Accordingly the invention is to be limited only in accordance with the scope of the appended claims.

I claim:

1. In combination in a compact actuator construction -of the class describedya reciprocable actuating plunger having abre at its forward endifor receiving a spring and rod; a rider carried by said plunger and slidable lengthwise thereon, said rider including a rod for entering said bore of said plunger, a coiled compression v8581118 the operating pin 2| of the unitary switch spring telescoping within said bore and over said rod for holding said rider forward on said -plungi er, a stop on said plunger for limiting the forward motion of the rider thereon, a spring op- 5 posing the forward motion of said rider and plunger, and a lever supported separately from said plunger and rider abutting said rider to be driven by the forward motion thereof.

2. In combination in s. compact actuator conl0 struction of the class described, a reciprocable actuating plunger having a bore at its forward end for receiving a spring and rod, a rider carried by said plunger and slidable lengthwise thereon, said rider including a rod for entering said bore of said plunger, a coiled compression spring telescoping Within said bore and over said rod for holding said rider forward on said plunger, said rider including also a striplying approximately parallel to and above said rod and plunger, and having its two ends turned down, the rear turned down end having a perforation that slidably ts over said plunger, the forward turned down end being fixed to said rod, a stop on said plunger for limiting the forward motion of the rider thereon, a bell crank supported separately from said plunger and rider on a pivot lying athwart and below said rod and plunger, said bell crank having an arm extending up alongside said rod and plunger and said strip, said strip having a shoulder at its edge for engaging said upward extending arm bf the bell crank for driving it in response to the' forward motion of said plunger, said upward extending arm of the bell crank having a tab extending from its upper end out over said strip so as to prevent said upper end of the bell crank from falling below said strip, and means for preventing rotation of said rider about the axis of said plunger and rod.

3. The combination of claim 1 wherein the spring for opposing the forward motion of said rider and plunger acts on said rider and therethrough upon said plunger, and wherein said lever is free from the restraint of said spring.

4. In combination in a compact actuator construction of the class described, a reciprocable actuating plunger having a bore ai; its forward end for receiving a spring and rod, a rider carried by said plunger and slidable lengthwise thereon, said rider including a rod for entering said bore of said plunger, a coiled compression spring telescoping over said rod and into said bore and thereby guiding said rod in said bore, a stop on said plunger for so limiting the forward motion of the rider thereon that said spring and rod telescope smoothly into said bore and insure that said rod cannot jam in the entrance of said bore, a spring urging said rider and plunger rearward, a. lever abutting said rider to be driven thereby, and means for guiding and laterally supporting the forward end of said rider as it moves with said plunger.

CARLTON B. MENSENKAMP. 

